1. The Field of the Invention
The present invention is in the field of dispensing devices and, more particularly, in the field of syringe devices configured to mix and dispense mixed compositions.
2. The Relevant Technology
Many reactive compositions are packaged in two parts, often known as xe2x80x9cA and B componentsxe2x80x9d or xe2x80x9cfirst and second materialsxe2x80x9d. Upon mixing, the A and B components undergo a chemical reaction that causes the resultant mixed composition to cure in some desired manner. In the dental field, for example, several mixed compositions currently enjoy wide use, such as cements and composite materials. Dental impression materials are also typically made using multiple components.
In order to function properly, the A and B components should be mixed together rapidly, thoroughly and in the appropriate proportions. Failure to mix the components rapidly can result in loss of valuable working time before the resultant mixed composition cures. In addition, failure to mix the components thoroughly or in the appropriate proportions can result in a composition having less than optimum characteristics. For instance, when a dental cement composition is either poorly mixed or includes the wrong proportions of A and B components, the cement can fail to obtain the chemical strength and/or adhesion properties required for a long-term bond.
One method for gauging and controlling the proportion of A and B components included in the mixed composition is to dispense the components from a pair of single dose syringes containing the appropriate proportions of the A and B components. Once dispensed, the components can then be mixed in a conventional manner, such as with a spatula or another stirring device in a mixing bowl or on a mixing pad. This additional mixing procedure, however, tends to be somewhat messy and time consuming. It is also difficult at times to ensure that the mixing has been sufficiently thorough.
Another method for delivering the A and B components is to use an existing double barrel syringe having two integrally connected syringes and a double plunger assembly for dispensing the contents from the barrels. Double barrel syringes are advantageous for enabling the components to be dispensed more quickly than with single syringes and for ensuring the A and B components are dispensed in the appropriate proportions, particularly when the syringes contain multiple doses. For instance, the double barrels of the syringes can be configured with large storage capacities for containing enough of the A and B components to be used for several doses or applications. Because the barrels are integrally connected, and assuming the plunger assembly is configured to dispense the contents from the barrels simultaneously, the appropriate mixing ratios of the components will be preserved regardless of the amount of the components dispensed from each barrel. The barrels of the syringe can also be coupled to an applicator tip, which is generally useful for initiating and facilitating the mixing of the A and B components inasmuch as the components come in contact within the applicator tip and therefore begin mixing before being dispensed.
One problem with existing double barrel syringes, however, is that they are not configured for being filled from the front or from the barrel tips. In particular, front filling existing double barrel syringes from the front can potentially lead to the introduction of the A and B components into the wrong barrels, because of the small size and proximity of the barrel tips. Introduction of the components into the wrong barrels can be problematic because it can result in premature curing of the components within the barrels. Accordingly, it is necessary to fill existing double barrel syringes that are configured with tips in close proximity from their backsides to avoid mixing the components during the filling process. Backside filling, however, may be undesirable because it can result in the formation of bubbles, air pockets and other pressure irregularities within the barrels which can cause spurting, irregular discharge, or otherwise prevent the A and B components from being dispensed in the appropriate proportions.
Pressure irregularities can also cause cross-migration and the premature curing of the A and B components within the opposing barrels. For example, a bubble existing in the A component barrel will be compressed when an adequate force is applied by the plunger assembly for expressing the A and B components. When the plunger assembly is released, however, the bubble within the A component barrel will expand, thereby forcing the plunger assembly to retract and creating a pressure void within the B component barrel. This pressure void naturally creates a suction force at the tip of the B component barrel which is sufficient to cause some of the residual A component to migrate backwards into the B component barrel where it can prematurely mix with the B component, cure, and inhibit or prevent future use of the syringe.
To avoid the aforementioned problems, some existing double barrel syringes are configured with tips that are spaced far apart so that they can be filled from the front. However, this spacing of the barrel tips also prevents the barrels from connecting with certain applicator tips for mixing purposes, thereby requiring the components to be mixed in an additional step after being dispensed from the barrels and prior to application. As mentioned above, this additional mixing step can be both time consuming and messy. Even if the spaced apart barrel tips are able to be connected to a separate mixing tube or tip, the A and B components must traverse interconnecting pathways existing between the barrel tips and the mixing tip before the components can be mixed, thereby resulting in inefficiencies and wasted product. In particular, the internal volume of the interconnecting pathways between the barrels and the applicator tip represents the volume of the components that will fail to be mixed or discharged from the syringe, and will therefore be wasted.
Yet another problem with integrally connected double barrel syringes is that they are often manufactured out of a single type of material, such as during an injection molding process. This may be economical for manufacturing purposes, but it can also preclude the use of certain inexpensive or desired materials. For instance, by way of example and not limitation, if it is desired to manufacture the syringe out of a transparent material but one component is photosensitive, the double barrel syringe cannot be manufactured out of a transparent material or else the one component will prematurely cure, even when the other component is not photosensitive. Likewise, if the one component adversely reacts with a certain type of material, that certain type of material cannot be used to manufacture the double barrel syringe, even if it will not react with the other component.
Accordingly, in view of the foregoing, there is currently a need in the art for improved dispensing devices and, more particularly, to syringe devices configured to dispense mixed compositions in a quick and convenient manner, while preserving the appropriate mixing ratios of the composition and while reducing any losses associated with transferring the components to an applicator tip. It would also be an advancement in the art to provide such improved syringe devices that have barrels that can be manufactured out of different materials to accommodate the different characteristics of the components that are contained therein.
Briefly summarized, presently preferred embodiments of the present invention are directed to improved syringe devices that are capable of dispensing the components of a mixed composition in appropriate proportions and of mixing the components prior to being dispensed. The syringe devices of the invention are also configured with tips that can be placed adjacently or in close proximity to reduce any losses associated with transferring the components to a mixing tip, while enabling the barrels to be filled from their tips. Certain improved syringe devices of the invention also include barrels that can be manufactured out of different materials to accommodate and preserve the different characteristics of the components that are contained within the barrels of the syringe devices.
According to one embodiment, the syringe devices of the invention include two barrels that are each configured for containing one of the two components of a mixed composition. The syringe devices also include barrel connecting means for detachably connecting the barrels. Barrel connecting means are useful for at least enabling the barrels to be separated so they can be filled from their front ends, regardless of the proximity of the barrel tips once the syringe device is completely assembled. Front filling the barrels with the corresponding components is also particularly useful for reducing any chance that bubbles or other pressure irregularities will be formed within the barrels during the filling process. In particular, the plunger can be pushed all the way into the barrel, expelling all the air, then retracted while the components are loaded from the tip. In contrast, backfilling requires the plunger to be inserted after filler, such that air can be introduced into the barrel during insertion of the plunger.
Barrel connecting means are also useful for enabling the barrels to be connected after filling to ensure the two components are dispensed in appropriate proportions, such as, for example, by a plunger assembly configured to simultaneously dispense the components from the two connected barrels. Barrel connecting means can include any combination of interesting ridge formations, snap formations, friction fitting stem and slot formations, an applicator tip, an applicator tip retaining collar, and the plunger assembly.
The plunger assembly generally includes two plungers that are configured for simultaneously expressing the first and second components out from the barrels. The plunger assembly also includes plunger coupling means for detachably coupling the first and second plungers together, which is useful for enabling the plungers to be separated without having to remove the plungers from the barrels, such as, for example, when the barrels are separated for filling. Plunger coupling means includes any combination of interesting ridge formations, snap formations, plunger caps, and friction fitting stem and slot formations.
According to one embodiment of the invention, the syringe device also includes an applicator tip configured to thoroughly mix and dispense the components contained in the barrels. The applicator tip is also configured for being placed over the tips of the barrels, which are disposed adjacently or in close proximity to minimize any losses associated with transferring the components to the applicator tip. According to one embodiment, the applicator tip includes internal mixing vanes specifically configured to ensure the components are thoroughly mixed before they are dispensed from the syringe device. The applicator tip is secured to the tips of the barrels with a retaining collar that is placed around the applicator tip and secured to structure on the barrels.
According to one embodiment of the invention, the barrels of the syringe device comprise at least one of different inner diameters, different colors, different transmissiveness and different material compositions. This embodiment is useful for enabling the barrels to be manufactured with desired materials, attributes and/or shapes to accommodate and preserve the different attributes of the components contained within the barrels. This is particularly useful, for example, to prevent premature curing of the individual components. This embodiment is also useful when the appropriate mixing ratios of the components are not one to one, in which case the barrels can be manufactured with different inner diameters to accommodate and preserve the appropriate mixing ratio of the desired composition.
These and other benefits, advantages and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
In order that the manner in which the above recited and other benefits, advantages and features of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
FIG. 1 illustrates a perspective view of one presently preferred embodiment of the syringe device of the invention that includes two detachably connecting barrels, two detachably connecting plungers of a plunger assembly, and an applicator tip;
FIG. 2 illustrates a perspective exploded view of one presently preferred embodiment of the syringe device of the invention that shows two plungers, two barrels, a plunger cap, an applicator tip and a retaining collar;
FIG. 3 illustrates one embodiment of a partially assembled syringe device of the invention that includes two plunger and barrel subassemblies, barrel coupling means and plunger coupling means configured to be detachably connected;
FIG. 4 illustrates the two plunger and barrel subassemblies shown in FIG. 3 that are detachably connected and with an applicator tip in position for being placed over the adjacently disposed tips of the barrels;
FIG. 5 illustrates the syringe device of FIG. 4 in which the applicator tip is connected to the barrels and in which a retaining collar is in position for being placed over the applicator tip;
FIG. 6 illustrates a syringe device in which the applicator tip comprises a mixing tip having internal mixing vanes configured for thoroughly mixing the components within the barrels with a retaining collar securing the applicator tip on the end of the barrels;
FIG. 7 illustrates one embodiment of the syringe device of the invention that includes one opaque barrel and one transparent barrel; and
FIG. 8 illustrates one embodiment of the syringe device of the invention that includes one barrel having a first inner diameter and a second barrel having a second inner diameter that is different than the first inner diameter.